Grinding wheel and method of making the same



May 25, 1937. D. E. WEBSTER 8 GRINDING WHEEL AND METHOD OF MAKING THESAME Filed Dec. 14, 1935 V ,1, 7 Mid Mivmama I [G .Z I I I INVENTOR"DUANE E. WEBSTER ATTORNEY Patented May 25, 11 937 I I 1 UNITED STATESFATEN-T OFFlCE GRINDING WHEEL AND METHOD OF MAKING THE SAME Duane E.Webster, ,Worcester,,Mass., assignor to Norton Company, Worcester,Mass., a corporation of Massachusetts Application December 14, 1935,Serial No. 54,427

' 2 Claims. (01. 51-278) The invention relates to grinding wheels, andas distinguished from vitrified ceramic bonds, and with regard to itsmore specific features, to also cements and sodium silicate, is that theor-. cutting-oil grinding wheels. ganic bonds are less brittle. Theystand the shock One object of the invention is to provide a of a blowbetter than the others. A cutting-off 5 faster cutting wheel. Anotherobject of the inwheel is preferably as thin as possible, because 5vention is to provide an improved method of makgrinding a wide slot ismerely power and mate ing a cutting-off wheel. Another object of therial wasting, since any slot will sufllce to cut off a invention is toprovide a cutting-off wheel that part. An organic bonded wheel can bemade develops less heat and is more dependable in thinner than avitrified wheel and still be satisoperation. Other objects will be inpart obvious factory on account of its greater resistance to 10 or inpart pointed out hereinafter. mechanical shock.

The invention accordingly consists in the fea- For the foregoing reasonsorganic bonded tures of construction, combinations of elements, wheelshave generally been used for cutting-off arrangements of parts, and inthe several steps wheels. But as ordinarily made, organic wheels andrelation and, order of each of said steps to have side surfaces thatembody the billiard table 5 one or more of the others thereof, all aswill be smoothness of the molds in which they are illustrativelydescribed herein, and the scope of pressed, due to the plasticity of thebond. the application of which will be pointed out in I mix the grainand the bond in any suitable the following claims. p or known manner. Ithen select a mold of the In the accompanying drawing in which is shownsize desired for the-production of a given size of 20 one embodiment ofthe invention, grinding wheel. A mold usually embodies a bot- Figure 1is an axial sectional view through a tom plate ID, a top plate H, a moldring I2 in the mold apparatus adapted to carry out the method internalbore of which the top and bottom plates of the invention; fit with aclose fit, and the mold also usually in- Figure 2 is an enlargedfragmentary sectional v-olves a central core l3 which fits in holes inthe 25 view, showing the action in the mold; top and bottom plates andwhich forms the Figure 3 is a sectional view througha cuttingcentralhole in the wheel. These parts have off grinding wheel. usually beenmade of iron or steel and have had I provide a suitable quantity ofabrasive grain smooth surfaces.

and a suitable quantity of bond. Any type or size I provide for the topand bottom plates of the 30 of abrasive grain may be used. Knownabrasive mold a piece of soft sheet material l5 of the same grainincludes aluminum oxide, silicon carbide} area as the grinding wheel tobe formed, that is quartz, emery, corundum, garnet, and diamond. to sayexactly covering the top surface of the Any of these may be used.Abrasives also include bottom plate and the bottom surface of the topboron carbide, and other carbides, such as tan-- plate. For thismaterial I prefer to use blotting 35 talum and tungsten. Any of thesemay be used. paper or I may use soft rubber or the like.

Abrasive grain of any size may be employed, but Assembling the moldexcept for the top plate so far as certain features of the invention areconi I, I place the annular disk of sheet material it, cerned, themedium or large sizes are preferred, blotting paper or the like, on thebottom plate to.

40 it being understood that the range of sizes de- I then introduce thedesired quantity of mixture 40 pends upon the material of the grain, thesize of 20 of abrasive grain and bond together with a the wheel, and thematerial being cut. The grain whatever plasticizer or temporary binderis used,

size of diamond for a carbide tool cut-oil wheel 7 if any. I level offthe wheel mixture. I then will in most cases be smaller than the grainsizes place on top of the wheel mixture the second sheet 5 for acutting-off wheel to out cold rolled steel bars, of blotting paper orthe like l5 which is preferably angles or the like. the same size andshape as the first sheet. I then Organic bonds may be used, and also anyother insert the top plate i i of the mold. bond which sets cold or at abaking as distin- .Subsequent operations may be the same as guished froma kiln temperature. In addition to according to previous practice. I maycold press the organic bonds I mention the various cements the mixturein a press of any desired description, 50 1 and sodium silicate. Iprefer, however, to use an forcing the top and bottom plates together toorganic bond. the limits desired. The abrasive grain being Organic bondsinclude rubber, shellac and synharder than the bond will project intothesoft thetic resins typified by phenol-formaldehyde material, viz. theblotting paper or rubber or resins. A characteristic'of these organicbonds the like, as clearly shown in Figure 2, and then 55 the mold maybe opened and the sides of the pressed or green wheel will show theabrasive grains 2| projecting from the mass. 1 may then place in avulcanizer if it is a rubber wheel or in a heat treating oven if it is aresin bonded wheel, and vulcanize or bake at the desired temperature andfor the desired length of time. The final finished product 25 is roughon the sides by roughness which is of the order of that of the abrasivegrains. It represents approximately a cross section through such anabrasive body as might be made without cutting the abrasive particles.

In carrying out the inventionI may use sheet material that is notentirely coterminous with the top and bottom plates if it is desired orsufilcient merely to produce a roughness on part of the area of thesides of the wheel.

I may mold the wheel mixture in a hot press if desired and in such casesuse a material and a temperature which do not result in destroying thematerial. For example, blotting paper may be used when hot pressing ataround 160 C. It is found that in either case the soft material may bereadily pried off the pressed wheel if it is removed from the mold, andin some cases may be lifted therefrom without prying. As the resultantwheel. has a natural roughness to each side thereof, -t cuts its waythrough a shaft or other shape without excessive heating due to sidefriction. There is alsoless tendency for the outer part to wear thin,whichcauses the wheel to wedge unless the side faces thereof areabradant. But in the case of the usual pressed wheel involvingan organicbond the side faces have been smooth and therefore non-abradant.

Instead of placing the blotting paper or other soft material in the moldas hereinbefore specifled, I may form the aforesaid natural roughness oneach side of the wheel, thus producing a rough sided wheel, as follows:Using rubber bond or bond having similar characteristics, I form amixture of the abrasive grains with the rubber in any desired manner.Several methods of doing this are now known 'to the art and I may useany of them. Having produced a mass of rubber and abrasive grains, Ipass the same through calendering rolls for the production of a thinsheet of still soft, unvulcanized rubber the mixture through thecalendering rolls, I place.

sheets of blotting paper or the like, one on each side of the mixture.Preferably the soft material such as the blotting paper specifled shouldbe. substantially coterminous with the mass of rubber and abrasive.

By reason of the calendering operation which reduces the thickness ofthe mass, the abrasive grains are forced into the soft material. As thematerial comes, from the calendering rolls the blotting paper or othersoft substance maybe readily peeled off of it on both sides. I then dieout the desired disk shapes, set the shapes on a batt, and vulcanizeaccording to known practice. The rubber mixture will preferably includean amount of sulphur, such as 20% or more, to form a hard rubber bonded.grinding wheel.

It will thus be seen that there has been provided by this invention amethod and a grinding wheel in which the various objects hereinabove setforth together with many thoroughly practical advantages aresuccessfully achieved. As various possible embodiments might be made ofthe mechanical features-of the above invention and as the art hereindescribed might be varied in various parts, all without departing fromthe scope of the invention, it is to be understood that all matterhereinbefore set forth is to be interpreted as illustrative and not in alimiting sense.

I claim:

1. Method of making a grinding wheel which comprises placing in a mold aquantity of abrasive grains and a plastic organic bond, placing againstthe bottom plate and top plate of the mold a sheet of soft compressiblesubstance, placing the mold in a press, pressing and indurating, wherebythere is formed a wheel in which abrasive grains project outwardly fromthe body thereof on the side faces of the wheel.

2. A cutting-oil! grinding wheel comprising abrasive grains bonded witha plastic organic bond very thin in comparison with its diameter andhaving rough side faces with individual abrasive grains projecting fromthe mass of abrasive grains and from the bond which is located invalleys between the abrasive grains. said cuttingoff grinding wheelbeing formed in a mold and pressed and indurated, and a sheet of softcompressible substance having been placed in the mold against the bottomplate and top plate DUANE E. I

